1. Field of the Invention
This invention relates to a small floating magnetic head device used for a magnetic disk drive and its attachment.
2. Description of the Related Art
Known floating magnetic head devices have a magnetic head attached to an end of a cantilever load arm through a holding member (generally called a "gimbal"). The magnetic head is suspended opposite a surface of a magnetic recording medium. A slider of the magnetic head is arranged to float over the magnetic recording medium with a very small clearance corresponding to a relative speed between the magnetic head and the magnetic recording medium.
Known composite magnetic heads have a slider formed by a nonmagnetic material, and installed with, for example, two air bearings. A magnetic core is inserted and secured in a slit provided in the trailing edge of one air bearing surface, i.e. the rearward edge of the slider with reference to the relative movement of the slider. The magnetic core consists of a pair of Mn--Zn monocrystal ferrite core pieces, between which a magnetic metal film, with a high saturation magnetic flux density, is interposed. A coil is wound around the magnetic core and secured in the slit. To wind the coil around the magnetic core, the slider has a vertical cut-out at the magnetic recording medium exit.
A holding member is interposed between the slider and a load arm. The holding member is provided with a pivot which serves as a support point for the load arm, and keeps the slider at a predetermined angle to the magnetic recording medium when the slider, which is attached to the holding member with adhesives, makes a movement relative to the magnetic recording medium. If the slider floats stably, a stable electromagnetic conversion characteristic can be obtained in recording and reproduction.
The floating magnetic head is attached to a substantially rectangular holding member. The back of the slider is installed on the load arm so that the slider floats over the magnetic disk at a very small clearance. In order for the slider to have a stable floating characteristic, the longitudinal center line of the holding member must be arranged to substantially coincide with that of the slider. Further, the attitude of the slider must be maintained close to parallel to the magnetic recording medium, and sufficient strength must be ensured to prevent the slider from dropping or becoming unbalanced due to partial peeling off. If too much adhesive is applied, to increase adhesive strength, it flows from the adhesive area and sticks onto the trailing edge of the slider. This generates stresses attracting the slider to the holding member which deforms the slider, deteriorating recording/reproducing characteristics.
Japanese U.M. laid open No. 63-87606 discloses that a slider may be prevented from deforming by balancing the rigidity of a pair of air bearings at the cut-out in the trailing edge of the slider. In this case, a reinforcing member is installed in the cut-out of the non-core air bearing at its trailing edge to make the slider rigid at each side and prevent deformation.
In a monolithic magnetic head, when the slider is fixed with adhesives on the holding member of the load arm, if the adhesives stick on the coil-wound portion, the core is pulled toward the holding member, and sagging or concave deformation occurs near the magnetic gap of a center rail. This causes the electromagnetic conversion characteristic to deteriorate. It has been proposed that a groove be provided on the adhering surface of the slider to prevent adhesives from sticking to the coil-wound portion, and to prevent the slider from being deformed (Japanese patent laid open No.4-6614).
In order for a magnetic disk drive to have higher recording density, higher transfer rate, and smaller size, the floating magnetic head must be smaller, have a lower flying height, and provide a more stable flying characteristics. A composite floating magnetic head has a length L of 4.3 mm, a width W of 3.2 mm, and a height H of 0.86 mm for a slider of 34 MIL size. The entire size of the composite floating magnetic head is reduced 70% for a 24 MIL size. A 19 MIL size, called a 50% slider, has a length of 2.1 mm, a width of 1.6 mm, and a height of 0.46 mm.
The flying height of the floating magnetic head must be around 0.1 .mu.m, preferably about 0.05-0.1 .mu.m, compared to the conventional 0.1-0.15 .mu.m. This size constraint requires high accuracy to maintain the predetermined flying height, and a small difference in flying height at each lateral end of the slider.
In the composite magnetic head, the magnetic core is generally inserted and fixed in only one air bearing of the slider at the trailing edge. The trailing edge of the other air bearing is provided with a cut-out, so that the trailing edge of the air bearing pair are not balanced for rigidity.
In addition, the slider has a lower rigidity as a whole because of its reduced size. The excessive adhesive, used for bonding the holding member and the slider, flows toward and sticks on the trailing edge of the slider. This stresses the slider, increasing deformation. This leads to differences in the deformation of the air bearing pair, which, if significant, increases flying height. As a result, difference in the flying height of the air bearing pair (flying height of each lateral end of the slider) is increased.
In solving such problems, a reinforcing member is typically provided in the cut-out in the trailing edge of the slider. But this decreases productivity by requiring more manufacturing steps. If a groove is provided in the slider attachment surface, it is insufficient to use adhesives to prevent slider deformation.